Facsimile apparatus



Jan. 10, 1956 J. BELL ET AL 2,729,818

FACSIMILE APPARATUS Filed July 31, 1953 United States Patent FACSIMILE APPARATUS John Bell, Beckenham, England, Frank H. Cannon, Chatswood, New South Wales, Australia, and Grahame Arthur Mundy, Beckenham, England, assignors to Muirhead & Co. Limited, Beckenham, England Application July 31, 1953, Serial No. 371,483 Claims priority, application Great Britain August 1, 1952 Claims. (Cl. 346-101) The invention relates to facsimile apparatus.

It is known in facsimile recorders to employ helical recording electrodes. Hitherto such electrodes have been mounted on a drum or on a helical support which in turn is mounted on a drum.

Moisture from the recording paper condenses on the drum and together with dust and residue from the paper will be urged against the electrode to cause portions of the helix to be insulated so that faulty electrical contact exists between the two electrodes. This faulty electrical contact between the electrodes establishes a high resistance between the electrodes and prevents an electrical signal from properly passing between them. This condition is known as blocking.

According to the invention, the helical electrode is mounted on a self-supporting helical structure. Thus the helical structure may have a helical surface supported by radial arms or a radial web.

The helical structure will, of course, be provided with appropriate centres or spindle ends on which it can rotate.

An advantage of the construction is a reduction of weight compared with the drum, and also a reduction of inertia which eases the problem of rapid starting such as occurs when a receiver is being phased with a transmitter whose drum is already rotating.

Further since only a helix is rotating there is no danger, as there may be with a drum or cylinder, of the paper contacting the moving part except at the desired point of contact.

An embodiment of the invention will be described with reference to the accompanying drawings.

Figure 1 is a side elevation partly sectioned;

Figure 2 is an end view;

Figure 3 is a detail.

2,729,818 Patented Jan. 10, 1956 In the drawings the helical structure is made of sections 1, each representing one sixth of the revolution of the helix. The sections are identical and are individually manufactured, for example, by die-casting. They are comprised of helical part 3 which is supported at its ends by radial arms 4 integrally formed on a hollow shaft 5. The sections are substantially spigoted as at 6 and are bolted together by bolts 7, or otherwise attached by known methods.

The detail (Figure 3) shows one method of attaching the helical electrode 2 by making this in the form of a strip of L-section and securing it by spaced screws along one limb of the L.

Various modifications may be made within the scope of the invention. Thus the electrode might be secured by riveting or by fixing under spring or screwed clamps.

What we claim is:

l. A helical recording electrode assembly for facsimile recorders comprising a plurality of identical sections, each representing a fraction of a single revolution of the helix and each comprising a rigid helical surface, helically disposed radial parts rigidly supporting the helical surface parts and a central shaft part carrying the radial means for securing the sections in abutting relaitonship with the helical surfaces in accurate alignment and a continuous helical electrode mounted on the aligned helical surfaces.

2. A supporting structure for a helical electrode for facsimile recorders as claimed in claim 1, in which the sections have spigots at one end and corresponding sockets at the other and adjacent sections are secured together by spaced bolts extending in the axial direction around the spigot joint.

3. A supporting structure for a helical electrode for facsimile recorders as claimed in claim 1, in which the radial parts are in the form of spaced radial arms.

4. A supporting structure for a helical electrode for facsimile recorders as claimed in claim 1, in which each section comprises one sixth of a revolution of the helix.

5. A supporting structure for a helical electrode for facsimile recorders as claimed in claim 1, in which the sections are die-cast.

References Cited in the file of this patent UNITED STATES PATENTS Kozak Oct. 28, 1941 

